We can take bets, but I guess a spark plug must have gone jammed after clogs weren't oiled, so the diesel wouldn't ignited and the plane crashed.
indeed, the mechanics was on vacation in the UK to check out cathedrals in small towns.
These plane things are terribly unreliable.
but for unknown reasons, the passengers refused to glide and decided to plunge the plane to wilfully die.
now, since they wilfully died, there is no reason to trigger further investigations.
And supreme leader Putin will seek damages from the families of the passengers, as they destroyed his plane.
Somewhat boring video of the parachute in action ("boring" being a synonym for "an amazing triumph of safety engineering"):
https://www.youtube.com/watch?v=gBCUQlF3MMU
14m video essay about the system:
https://www.youtube.com/watch?v=zT58pzY41wA
(Reporting says this was an Embraer, this is strictly a tangent.)
I also am unsure how you are supposed to "oil the clogs" to prevent "jamming"